Cardiorespiratory Adaptations to Training at Specified Intensities

Sixteen college men were randomly divided into three training groups and one control group in a study of selected cardiorespiratory adaptations to six weeks of training exercises eliciting either 120, 150, or 180 heart rates. Training consisted of walking on the motor driven treadmill for 10 min. a day, 3 days per week. Highly significant differences were found in the analysis of pre-post Balke treadmill test scores. The Åstrand-Ryhming nomogram prediction of aerobic capacity also showed highly significant changes due to training. Analysis of group differences revealed that the 180 training group's improvement was significantly different from all other groups in both tests. The 150 group was found to be significantly different from the 120 and control groups in the Balke test analysis. No changes were noted in resting pulse rate nor in the pulse rate—oxygen consumption relationship. However, there were small positive differences in the grade required to elicit the training heart rates. The study supports the hypothesis that intense activity is necessary to bring about the changes associated with cardiorespiratory endurance.